U.S. patent application number 17/268720 was filed with the patent office on 2021-08-12 for connection establishment.
The applicant listed for this patent is Nokia Technologies Oy. Invention is credited to Vinh Van Phan, Ling Yu.
Application Number | 20210251023 17/268720 |
Document ID | / |
Family ID | 1000005582678 |
Filed Date | 2021-08-12 |
United States Patent
Application |
20210251023 |
Kind Code |
A1 |
Phan; Vinh Van ; et
al. |
August 12, 2021 |
CONNECTION ESTABLISHMENT
Abstract
There is provided a method at a first user equipment, the method
comprising: deciding to set up a unicast sidelink, SL, connection
with a second user equipment; determining whether or not a radio
access network serving the first user equipment or a radio access
network serving the second user equipment is able to assist in
setting up the unicast SL connection; performing one of the
following: upon determining the positive, applying a L1
unicast-based SL connection for setting up the unicast SL
connection, upon determining the negative, applying a L1
broadcast-based SL connection for setting up the unicast SL
connection; and communicating with the second user equipment over
the unicast SL.
Inventors: |
Phan; Vinh Van; (Oulu,
FI) ; Yu; Ling; (Kauniainen, FI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Nokia Technologies Oy |
Espoo |
|
FI |
|
|
Family ID: |
1000005582678 |
Appl. No.: |
17/268720 |
Filed: |
September 24, 2019 |
PCT Filed: |
September 24, 2019 |
PCT NO: |
PCT/FI2019/050683 |
371 Date: |
February 16, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62741640 |
Oct 5, 2018 |
|
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|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W 76/40 20180201;
H04W 4/40 20180201; H04W 72/04 20130101; H04W 76/10 20180201 |
International
Class: |
H04W 76/10 20060101
H04W076/10; H04W 72/04 20060101 H04W072/04; H04W 76/40 20060101
H04W076/40; H04W 4/40 20060101 H04W004/40 |
Claims
1. A method at a first user equipment, the method comprising:
deciding to set up a unicast sidelink (SL) connection with a second
user equipment; determining whether or not a radio access network
serving the first user equipment or a radio access network serving
the second user equipment is able to assist in setting up the
unicast SL connection; performing one of the following: upon
determining the positive, applying a layer 1 (L1) unicast-based SL
connection for setting up the unicast SL connection, upon
determining the negative, applying a L1 broadcast-based SL
connection for setting up the unicast SL connection; and
communicating with the second user equipment over the unicast
SL.
2. The method of claim 1, further comprising: determining an
application requesting the connection; and performing the deciding
based on the application, wherein the application requires the
unicast SL connection if the application is triggered by the first
user equipment for assistance in at least partly autonomous
driving; and/or wherein the application requires the unicast SL if
the application is at least one of a group comprising: a
see-through application and a line-switching application.
3.-4. (canceled)
5. The method of claim 1, wherein the determining comprises
receiving, from the radio access network serving the first
vehicular user equipment, an indication of a support for setting up
the L1 unicast-based SL connection.
6.-7. (canceled)
8. The method of claim 1, further comprising: determining that the
radio access network serving the first user equipment is able to
assist in setting up the L1 unicast SL connection; sending to the
second user equipment, an establishment request for the L1
unicast-based SL connection, wherein the establishment request
comprises at least one locally unique identifier for the L1
unicast-based SL connection and a resource allocation for the L1
unicast-based SL connection corresponding to the at least one
locally unique ID; and communicating with the second user equipment
over the L1 unicast-based SL connection.
9. (canceled)
10. The method of claim 8, further comprising: receiving an
establishment response from the second user equipment; determining
from the establishment response that the second user equipment is
served by the same radio access network as the first user
equipment; and sending, to the radio access network serving the
first user equipment, an indication of the identity of the second
user equipment.
11. The method of claim 1, further comprising: determining that the
radio access network serving the first user equipment is unable to
assist; proactively reserving resources for the unicast SL
connection before the SL connection is set up; sending to the
second user equipment, an establishment request for the unicast SL
connection; and including an indication of the resources in the
establishment request.
12. (canceled)
13. The method of claim 11, further comprising: receiving an
establishment response from the second user equipment indicating
that the radio access network of the second user equipment is able
to assist in setting up the L1 unicast-based SL connection, wherein
the establishment response includes at least one locally unique
identifier to be applied for the L1 unicast-based SL connection;
and communicating with the second user equipment over the L1
unicast-based SL connection, instead of the L1 broadcast-based SL
connection.
14. An apparatus, comprising: at least one processor and at least
one memory including a computer program code, wherein the at least
one memory and the computer program code are configured, with the
at least one processor, to cause a first user equipment to perform
operations comprising: deciding to set up a unicast sidelink (SL)
connection with a second user equipment; determining whether or not
a radio access network serving the first user equipment or a radio
access network serving the second user equipment is able to assist
in setting up the unicast SL connection; performing one of the
following: upon determining the positive, applying a layer 1 (L1)
unicast-based SL connection for setting up the unicast SL
connection, upon determining the negative, applying a L1
broadcast-based SL connection for setting up the unicast SL
connection; and communicating with the second user equipment over
the unicast SL.
15. The apparatus of claim 14, wherein the at least one memory and
the computer program code are configured, with the at least one
processor, to cause the first user equipment to perform operations
comprising: determining an application requesting the connection;
and performing the deciding based on the application, wherein the
application requires the unicast SL connection if the application
is triggered by the first user equipment for assistance in at least
partly autonomous driving; and/or wherein the application requires
the unicast SL connection if the application is at least one of a
group comprising: a see-through application and a line-switching
application.
16.-17. (canceled)
18. The apparatus of claim 14, wherein the determining comprises
receiving, from the radio access network serving the first
vehicular user equipment, an indication of a support for setting up
the L1 unicast-based SL connection.
19. The apparatus of claim 14, wherein the at least one memory and
the computer program code are configured, with the at least one
processor, to cause the first user equipment to perform operations
comprising: determining that the radio access network serving the
first user equipment is able to assist in setting up the L1 unicast
SL connection; requesting from the radio access network serving the
first user equipment at least one locally unique identifier to be
applied for the L1 unicast-based SL connection; and receiving the
at least one locally unique identifier from the radio access
network serving the first user equipment.
20. The apparatus of claim 19, wherein the at least one memory and
the computer program code are configured, with the at least one
processor, to cause the first user equipment to perform operations
comprising: requesting from the radio access network serving the
first user equipment a resource allocation for the L1 unicast-based
SL connection; and receiving the resource allocation for the L1
unicast-based SL connection from the radio access network serving
the first user equipment.
21. The apparatus of claim 14, wherein the at least one memory and
the computer program code are configured, with the at least one
processor, to cause the first user equipment to perform operations
comprising: determining that the radio access network serving the
first user equipment is able to assist in setting up the L1 unicast
SL connection; sending to the second user equipment, an
establishment request for the L1 unicast-based SL connection; and
communicating with the second user equipment over the L1
unicast-based SL connection.
22. The apparatus of claim 21, wherein the establishment request
comprises at least one locally unique identifier for the L1
unicast-based SL connection and a resource allocation for the L1
unicast-based SL connection corresponding to the at least one
locally unique ID.
23. The apparatus of claim 21, wherein the at least one memory and
the computer program code are configured, with the at least one
processor, to cause the first user equipment to perform operations
comprising: receiving an establishment response from the second
user equipment; determining from the establishment response that
the second user equipment is served by the same radio access
network as the first user equipment; and sending, to the radio
access network serving the first user equipment, an indication of
the identity of the second user equipment.
24. The apparatus of claim 14, wherein the at least one memory and
the computer program code are configured, with the at least one
processor, to cause the first user equipment to perform operations
comprising: determining that the radio access network serving the
first user equipment is unable to assist; and sending to the second
user equipment, an establishment request for the unicast SL
connection.
25. The apparatus of claim 24, wherein the at least one memory and
the computer program code are configured, with the at least one
processor, to cause the first user equipment to perform operations
comprising: proactively reserving resources for the unicast SL
connection before the SL connection is set up; and including an
indication of the resources in the establishment request.
26. The apparatus of claim 24, wherein the at least one memory and
the computer program code are configured, with the at least one
processor, to cause the first user equipment to perform operations
comprising: receiving an establishment response from the second
user equipment indicating that the radio access network of the
second user equipment is able to assist in setting up the L1
unicast-based SL connection, wherein the establishment response
includes at least one locally unique identifier to be applied for
the L1 unicast-based SL connection; and communicating with the
second user equipment over the L1 unicast-based SL connection,
instead of the L1 broadcast-based SL connection.
27. The apparatus of claim 14, wherein the apparatus is or is
comprised in the first user equipment.
28.-30. (canceled)
31. An apparatus, comprising at least one processor and at least
one memory including a computer program code, wherein the at least
one memory and the computer program code are configured, with the
at least one processor, to cause a second user equipment to perform
operations comprising: receiving an establishment request for a
unicast sidelink (SL) connection establishment from the first user
equipment, the request indicating whether the first user equipment
is able to enforce a layer 1 (L1) unicast-based SL connection or
not; upon detecting that the first user equipment is able to
enforce the L1 unicast-based SL connection, performing the
following: extracting from the establishment request at least one
locally unique identifier for the L1 unicast-based SL connection
and a resource allocation for the SL communication corresponding to
the at least one locally unique identifier, and communicating with
the first user equipment over the L1 unicast-based SL connection;
upon detecting that the first user equipment is not able to enforce
the L1 unicast-based SL connection, performing the following:
determining whether a radio access network serving the second user
equipment is able to assist in setting up the L1 unicast SL
connection or not; upon determining the positive, performing the
following: requesting and receiving from the radio access network
serving the second user equipment at least one at least one locally
unique identifier for the L1 unicast-based SL connection,
responding to the first user equipment, wherein the response
includes the at least one locally unique identifier and a resource
allocation for the SL communication corresponding to the at least
one locally unique identifier, and communicating with the first
user equipment over the L1 unicast-based SL connection; upon
determining the negative, performing the following: communicating
with the first user equipment over a L1 broadcast-based SL
connection.
32. (canceled)
Description
TECHNICAL FIELD
[0001] Various example embodiments relate generally to connection
establishment, e.g. between mobile or vehicular devices.
BACKGROUND
[0002] It is important to set up a connection between two devices
reliably. Also, in some cases, it may be important to set up the
connection fast. This may be the case with applications requiring
ultra-reliable low latency communications (URLLC). One use case
where such use cases are present is vehicular communications.
SUMMARY
[0003] According to some aspects, there is provided the subject
matter of the independent claims. Some further aspects are defined
in the dependent claims.
LIST OF THE DRAWINGS
[0004] In the following, the invention will be described in greater
detail with reference to the embodiments and the accompanying
drawings, in which
[0005] FIG. 1A presents a communication network, according to some
embodiments;
[0006] FIG. 1B presents a communication network, according to some
embodiments;
[0007] FIG. 2A shows a use case to which the embodiments may be
applicable to;
[0008] FIG. 2B shows a use case to which the embodiments may be
applicable to;
[0009] FIG. 3 shows a method, according to an embodiment;
[0010] FIG. 4 illustrates a signaling flow diagram, according to
some embodiments;
[0011] FIG. 5 illustrates a signaling flow diagram, according to
some embodiments;
[0012] FIG. 6 illustrates a signaling flow diagram, according to
some embodiments;
[0013] FIG. 7 depicts an apparatus, according to some embodiments;
and
[0014] FIG. 8 depicts an apparatus, according to some
embodiments.
DESCRIPTION OF EMBODIMENTS
[0015] The following embodiments are exemplary. Although the
specification may refer to "an", "one", or "some" embodiment(s) in
several locations of the text, this does not necessarily mean that
each reference is made to the same embodiment(s), or that a
particular feature only applies to a single embodiment. Single
features of different embodiments may also be combined to provide
other embodiments.
[0016] Embodiments described may be implemented in a radio system,
such as one comprising at least one of the following radio access
technologies (RATs): Worldwide Interoperability for Micro-wave
Access (WiMAX), Global System for Mobile communications (GSM, 2G),
GSM EDGE radio access Network (GERAN), General Packet Radio Service
(GRPS), Universal Mobile Telecommunication System (UMTS, 3G) based
on basic wideband-code division multiple access (WCDMA), high-speed
packet access (HSPA), Long Term Evolution (LTE), LTE-Advanced, and
enhanced LTE (eLTE), wireless local area network (WLAN or WiFi),
Bluetooth.RTM., personal communications services (PCS),
ZigBee.RTM., systems using ultra-wideband (UWB) technology, sensor
networks, mobile ad-hoc networks (MANETs) and Internet Protocol
multimedia subsystems (IMS) or any combination thereof. Term `eLTE`
here denotes the LTE evolution that connects to a 5G core. LTE is
also known as evolved UMTS terrestrial radio access (EUTRA) or as
evolved UMTS terrestrial radio access network (EUTRAN).
[0017] The embodiments are not, however, restricted to the
systems/RATs given as an example but a person skilled in the art
may apply the solution to other communication systems provided with
necessary properties. One example of a suitable communications
system is the 5G system. The 3GPP solution to 5G is referred to as
New Radio (NR). 5G has been envisaged to use
multiple-input-multiple-output (MIMO) multi-antenna transmission
techniques, more base stations or nodes than the current network
deployments of LTE (a so-called small cell concept), including
macro sites operating in co-operation with smaller local area
access nodes and perhaps also employing a variety of radio
technologies for better coverage and enhanced data rates. 5G will
likely be comprised of more than one radio access technology/radio
access network (RAT/RAN), each optimized for certain use cases
and/or spectrum. 5G mobile communications may have a wider range of
use cases and related applications including video streaming,
augmented reality, different ways of data sharing and various forms
of machine type applications, including vehicular safety, different
sensors and real-time control. 5G is expected to have multiple
radio interfaces, namely below 6 GHz, cmWave and mmWave, and being
integradable with existing legacy radio access technologies, such
as the LTE.
[0018] The current architecture in LTE networks is distributed in
the radio and centralized in the core network. The low latency
applications and services in 5G require to bring the content close
to the radio which leads to local break out and multi-access edge
computing (MEC). 5G enables analytics and knowledge generation to
occur at the source of the data. This approach requires leveraging
resources that may not be continuously connected to a network such
as laptops, smartphones, tablets and sensors. MEC provides a
distributed computing environment for application and service
hosting. It also has the ability to store and process content in
close proximity to cellular subscribers for faster response time.
Edge computing covers a wide range of technologies such as wireless
sensor networks, mobile data acquisition, mobile signature
analysis, cooperative distributed peer-to-peer ad hoc networking
and processing also classifiable as local cloud/fog computing and
grid/mesh computing, dew computing, mobile edge computing,
cloudlet, distributed data storage and retrieval, autonomic
self-healing networks, remote cloud services, augmented and virtual
reality, data caching, Internet of Things (massive connectivity
and/or latency critical), critical communications (autonomous
vehicles, traffic safety, real-time analytics, time-critical
control, healthcare applications). Edge cloud may be brought into
RAN by utilizing network function virtualization (NVF) and software
defined networking (SDN). Using edge cloud may mean access node
operations to be carried out, at least partly, in a server, host or
node operationally coupled to a remote radio head or base station
comprising radio parts. Network slicing allows multiple virtual
networks to be created on top of a common shared physical
infrastructure. The virtual networks are then customised to meet
the specific needs of applications, services, devices, customers or
operators.
[0019] For 5G networks, it is envisaged that the architecture may
be based on a so-called CU-DU (central unit--distributed unit)
split, where one gNB-CU controls several gNB-DUs. The term `gNB`
may correspond in 5G to the eNB in LTE. The gNBs (one or more) may
communicate with one or more UEs. The gNB-CU (central node) may
control a plurality of spatially separated gNB-DUs, acting at least
as transmit/receive (Tx/Rx) nodes. In some embodiments, however,
the gNB-DUs (also called DU) may comprise e.g. a radio link control
(RLC), medium access control (MAC) layer and a physical (PHY)
layer, whereas the gNB-CU (also called a CU) may comprise the
layers above RLC layer, such as a packet data convergence protocol
(PDCP) layer, a radio resource control (RRC) and an internet
protocol (IP) layers. Other functional splits are possible too. It
is considered that skilled person is familiar with the OSI model
and the functionalities within each layer.
[0020] The plurality of gNBs (access points/nodes), each comprising
the CU and one or more DUs, may be connected to each other via the
Xn interface over which the gNBs may negotiate. The gNBs may also
be connected over next generation (NG) interfaces to a 5G core
network (5GC), which may be a 5G equivalent for the core network of
LTE. Such 5G CU-DU split architecture may be implemented using
cloud/server so that the CU having higher layers locates in the
cloud and the DU is closer to or comprises actual radio and antenna
unit. There are similar plans ongoing for LTE/LTE-A/eLTE as well.
When both eLTE and 5G will use similar architecture in a same cloud
hardware (HW), the next step may be to combine software (SW) so
that one common SW controls both radio access networks/technologies
(RAN/RAT). This may allow then new ways to control radio resources
of both RANs. Furthermore, it may be possible to have
configurations where the full protocol stack is controlled by the
same HW and handled by the same radio unit as the CU.
[0021] It should also be understood that the distribution of labour
between core network operations and base station operations may
differ from that of the LTE or even be non-existent. Some other
technology advancements probably to be used are Big Data and
all-IP, which may change the way networks are being constructed and
managed. 5G (or new radio, NR) networks are being designed to
support multiple hierarchies, where MEC servers can be placed
between the core and the base station or nodeB (gNB). It should be
appreciated that MEC can be applied in 4G networks as well.
[0022] 5G may also utilize satellite communication to enhance or
complement the coverage of 5G service, for example by providing
backhauling. Possible use cases are providing service continuity
for machine-to-machine (M2M) or Internet of Things (IoT) devices or
for passengers on board of vehicles, or ensuring service
availability for critical communications, and future
railway/maritime/aeronautical communications. Satellite
communication may utilize geostationary earth orbit (GEO) satellite
systems, but also low earth orbit (LEO) satellite systems, in
particular mega-constellations (systems in which hundreds of
(nano)satellites are deployed). Each satellite in the
mega-constellation may cover several satellite-enabled network
entities that create on-ground cells. The on-ground cells may be
created through an on-ground relay node or by a gNB located
on-ground or in a satellite.
[0023] The embodiments may be also applicable to narrow-band (NB)
Internet-of-things (IoT) systems which may enable a wide range of
devices and services to be connected using cellular
telecommunications bands. NB-IoT is a narrowband radio technology
designed for the Internet of Things (IoT) and is one of
technologies standardized by the 3rd Generation Partnership Project
(3GPP). Other 3GPP IoT technologies also suitable to implement the
embodiments include machine type communication (MTC) and eMTC
(enhanced Machine-Type Communication). NB-IoT focuses specifically
on low cost, long battery life, and enabling a large number of
connected devices. The NB-IoT technology is deployed "in-band" in
spectrum allocated to Long Term Evolution (LTE)--using resource
blocks within a normal LTE carrier, or in the unused resource
blocks within a LTE carrier's guard-band--or "standalone" for
deployments in dedicated spectrum.
[0024] Direct mobile device-to-device (D2D) communications, or D2D
for short in the following, can also be setup between communication
devices. It is noted that direct communications between devices can
be referred to in various terms, for example as mobile-to-mobile
(M2M), machine-to-machine (M2M), terminal-to-terminal (T2T) or
peer-to-peer (P2P). Let us in the following refer to such
communication with term D2D. D2D communications can use licensed
radio spectrum under supervision and control of at least one
supporting system, typically a cellular system but other type of
supporting systems are possible too, such as wireless local area
network (WLAN/WiFi). D2D may use, at least for a part of the needed
resources, the same radio resources of the supporting system or
systems. Direct D2D communications can be incorporated into the
cellular network for example to reduce transmitter power
consumption in the participating communication devices and the
network side, to improve spectrum efficiency, to increase cellular
network capacity and coverage, and to create and support more
services for users in an efficient fashion. The resources may be
common resources shared by many devices or dedicated resources
allocated to the pair of devices participating the D2D
communication by a radio access network (RAN) as the supporting
system.
[0025] FIGS. 1A and 1B illustrate examples of communication systems
to which embodiments of the invention may be applied. Let us look
at FIG. 1A. The system may comprise a control node 110 providing a
cell 100. Each cell may be, e.g., a macro cell, a micro cell,
femto, or a pico cell, for example. In another point of view, the
cell may define a coverage area or a service area of the access
node 110. The control node 110 may be an evolved Node B (eNB) as in
the LTE and LTE-A, ng-eNB as in eLTE, gNB of 5G, or any other
apparatus capable of controlling radio communication and managing
radio resources within a cell. For 5G solutions, the implementation
may be similar to LTE-A, or e.g. apply virtualized networks. The
control node 110 may be called a base station, network node, or an
access node.
[0026] Although not shown, one or more local area access nodes may
be arranged within a control area of a macro cell access node. The
local area access node may provide wireless access within a
sub-cell that may be comprised within a macro cell. Examples of the
sub-cell may include a micro, pico and/or femto cell. Typically,
the sub-cell provides a hot spot within a macro cell. The operation
of the local area access node may be controlled by an access node
under whose control area the sub-cell is provided.
[0027] The system may be a cellular communication system composed
of a radio access network of access nodes, each controlling a
respective cell or cells. The access node 110 may provide user
equipment 120 (also called UE, user device, user terminal, terminal
device, mobile termination, subscriber unit, mobile station, remote
terminal, access terminal, etc.) with wireless access to other
networks such as the Internet. The wireless access may comprise
downlink (DL) communication from the control node 110 to the UE 120
and uplink (UL) communication from the UE 120 to the control node
110. The UE typically refers to a portable computing device that
includes wireless mobile communication devices operating with or
without a subscriber identification module (SIM), including, but
not limited to, the following types of devices: a mobile station
(mobile phone), smartphone, personal digital assistant (PDA),
handset, device using a wireless modem (alarm or measurement
device, etc.), laptop and/or touch screen computer, tablet, game
console, notebook, vehicular device, and multimedia device.
[0028] For D2D communications, there may be at least a second UE
122, which may also be served by the control node 110. the second
UE 122 may further perform D2D communication with the first UE 120.
This connection between the two UEs may be called a sidelink
(SL).
[0029] In FIG. 1B, the situation may differ in that the UES 120,
122 may be served by different cells 100, 102, and/or by different
RATs and/or by different operators, e.g. in case where the control
nodes 110, 112 do not belong to same radio access
networks/operators.
[0030] In the case of multiple access nodes in the communication
network, the access nodes may be connected to each other with an
interface. LTE specifications call such an interface as X2
interface. In connection of IEEE 802.11 network (i.e. wireless
local area network, WLAN, WiFi), a similar interface Xw may be
provided between access points. An interface between an eLTE access
point and a 5G access point may be called Xn. Other communication
methods between the access nodes may also be possible.
[0031] The access node 110 may be further connected via another
interface to a core network of the cellular communication system.
The LTE specifications specify the core network as an evolved
packet core (EPC), and the core network may comprise a mobility
management entity (MME) and a gateway node. The MME may handle
mobility of terminal devices in a tracking area encompassing a
plurality of cells and handle signalling connections between the
terminal devices and the core network. The gateway node may handle
data routing in the core network and to/from the terminal devices.
The 5G specifications specify the core network as a 5G core (5GC),
and the core network may comprise an access and mobility management
entity (AMF) and a gateway node. The AMF may handle mobility of
terminal devices in a tracking area encompassing a plurality of
cells and handle signalling connections between the terminal
devices and the core network. The gateway node may handle data
routing in the core network and to/from the terminal devices.
[0032] Vehicular communication systems are networks in which
vehicles and road-side units are the communicating nodes, providing
each other with information, such as safety warnings and traffic
information. They can be effective in avoiding accidents and
traffic congestion. V2V (vehicle to vehicle) is an automobile
technology designed to allow automobiles to "talk" to each other.
In this sense, V2V resembles D2D communication. Term V2I (vehicular
to infrastructure) allows the vehicular devices to communicate with
network, such as with roadside access nodes. I.e. V2I may be seen
as a communication model that allows vehicles to share information
with the components that support a high-way system. Such components
include overhead RFID readers and cameras, traffic lights, lane
markers, streetlights, signage and parking meters. V2I
communication is typically wireless and bi-directional: data from
infrastructure components can be delivered to the vehicle over an
ad hoc network and vice versa. Together V2V and V2I may be called
V2X.
[0033] 3GPP NR V2X considers support for advanced use cases
including cooperative driving use cases such as cooperative
perception (see-through) and cooperative maneuvering
(lane-merging/switching). Taking the see-through use case as one
example shown in FIG. 2A, the vehicle 120, which is blocked of the
sight and experiencing a loss of visibility, may request one or
more vehicles 122 in front to provide vision-enhancing and/or
see-through video streaming over the SL connection. In this case,
the requesting end 120 is the content receiver and the requested
end 122 is the content provider. This session may be a short- or a
long-living one, depending on road traffic condition and traveling
path of involved vehicles. Taking the lane-merging/changing use
case shown in FIG. 2B for another example, the vehicle 120 which
wants to change the lane need to request and agree with one or more
impacted vehicles 122 over SL to make proper room or keep proper
distance for the requesting vehicle 120 to change the lane. This
session may be a short-living one. The vehicles of FIGS. 2A and 2B
may be seen as the UEs of FIG. 1A, as the V2V communication needed
in FIGS. 2A and 2B is one embodiment of the general D2D
communication established between UEs 120, 122 in FIG. 1A.
Likewise, also in the vehicular cases of FIGS. 2A and 2B, the
vehicles 120, 122 may be served by different cells and/or RATs
and/or by different operators. Therefore, the vehicles of FIGS. 2A
and 2B may also be called UEs, terminal devices, etc, and be
referred with the same reference numerals as the UEs in FIGS. 1A
and 1B.
[0034] It has been established that, for such use cases which
involve at least two particular vehicles traveling on road in
proximity of each other, a high-reliability and low-latency
communication (HRLLC) or URLLC sessions are needed. Hence, it is
important to enable a quick setup of such a challenging HRLLC
communication session for a cooperative driving event which is
initiated dynamically on-the-fly between the involved or impacted
vehicles' UEs. It is noted that the impacted UEs are rather random,
determined on-the-fly along with service availability. The impacted
vehicles can be subscribers of different operators, referred to as
the multi-operator issue. Furthermore, a support for
out-of-coverage operation may need to be considered for V2X. Hence,
direct D2D based communications is a preferable option, as opposed
to options based on conventional network access via e.g. a roadside
network access node.
[0035] For providing HRLLC for supporting such advanced V2X use
cases addressed herein, a network-assisted layer 1 (L1)
unicast-based SL, as opposed to current L1 broadcast-based SL, may
be preferable.
[0036] The L1 unicast-based SL is referred to as a SL
transmission/reception scheme in which L1 scheduling assignment
(SA) for the SL transmission is addressed to a locally unique
access-stratum (AS) UE identifier (ID) or SL ID of an intended
receiver or a group of receivers. This may resemble to that of the
network-scheduled transmission/reception using a physical downlink
control channel (PDCCH) addressed to unique cell-specific radio
network temporary identifiers (RNTIs) of scheduled UEs in LTE, for
example. The network may assist in resolving collisions in
resources and/or locally unique UE IDs or SL IDs for L1
unicast-based SLs. It is noted that L1 unicast-based SL may support
multicast/broadcast as well, using locally unique UE ID or SL ID
common to a specific group of receiving UEs or all receiving
UEs.
[0037] On the other hand, L1 broadcast-based SL is referred to a
scheme used in the current LTE in which L1 SA of a SL transmission
is: either addressed to all, i.e., there is no UE ID of intended
receiver is included in SA; or to all of those UEs which randomly
share the same part of the UE ID of intended receiver(s) included
in the SA. In the latter case, LTE SL solution is one example, i.e.
the UE ID included in SA is the 8 low-significant bits (LSB) of a
24-bits long non-access-stratum (NAS) ID or of an application UE ID
of the intended receiver or group of receivers.
[0038] In the current LTE V2X, SL is fully broadcast and
transmitter-oriented. That is, the transmitter is just broadcasting
V2X messages over SL without a need of knowing about any specific
receivers. It is further noted that realizing such L1 unicast-based
SL for autonomous D2D communications is rather problematic because
of difficulty in assigning a locally unique UE ID or SL ID for SA.
The alternative of using a globally unique UE ID, such as the NAS
ID or the application ID for SA, is not a preferable option due to
high signalling overhead as well as security reason.
[0039] Hence, how to efficiently establish the L1 unicast-based SL
connection whenever seen appropriate remains an unsolved issue to
which the embodiments presented herein may address. Therefore, the
embodiments consider RAN-level enhancements for speeding up the
setup of a SL based communication session for the aforementioned
cooperative driving use cases, e.g. when using network-assisted L1
unicast SL and taking into account application awareness of the
targeted use cases. In other words, L1 unicast-based SL may be
primarily used for facilitating advanced V2X use cases with certain
applications, while co-existing with the current L1 broadcast-based
SL.
[0040] It needs to be noted that in the current LTE Proximity
Services (ProSe), SL is of L1 broadcast nature and hence unicast
communication over SL can only be supported on higher layer,
starting from application layer and stopping at layer 2 (L2). The
setup of unicast communication over SL in this case is relied on
control protocol above the access stratum and thus does not need
RAN-level network assistance. On the other hand, framework of
network-assisted D2D communications considers L1 unicast-based D2D.
There the setup of L1 unicast-based D2D between two UEs in
proximity of one another may be fully controlled by a serving RAN
and therefore not involve a SL application control protocol at all.
The setup may require extensive RAN-level signalling between the
involved UEs and between each of the involved UEs and the serving
RAN. Furthermore, the multi-operator issue depicted in FIG. 1B is
rather problematic that requires notable coordination between
involved networks.
[0041] To at least partially tackle these problems, there is
proposed a solution for expediting setup of unicast communications
over SL, e.g. for predetermined V2X use cases including cooperative
driving use cases such as cooperative perception (see-through) and
cooperative maneuvering (lane-merging/switching). The solution may
comprise e.g. (i) triggers for involved or impacted UEs/vehicles to
determine whether the needed unicast D2D connection shall be based
on the L1 broadcast-based SL or the L1 unicast-based SL, and (ii)
RAN-level signalling enhancements for facilitating and fastening
the setup of the needed unicast D2D communication session. The
proposed solution may in an embodiment be based on exploring
application contexts of targeted use cases coupled with UE contexts
of involved UEs 120,122 as well as availability of network
assistance from a serving RAN of either of the involved UEs. The
most appropriate and suitable SL connection may be e.g. either
network-assisted or autonomous and either using L1 unicast-based SL
or L1 broadcast-based SL, for the intended on-the-fly session as
quick as possible.
[0042] FIG. 3 depicts an example method. The method may be
performed by a first vehicular apparatus/device, such as the
UE/vehicle 120 of FIG. 2A and/or 2B. This first UE 120 may be the
initiator or requesting UE that initiates or requests the setup of
the unicast D2D communication session for the needed
application.
[0043] Accordingly, as shown in FIG. 3, the first vehicle 120 may
in step 300 decide to set up a unicast sidelink (SL) connection
with a second device, such as with the UE/vehicle 122 of FIG. 2A
and/or 2B.
[0044] In step 302, the first device 120 may determine whether or
not a RAN serving the first device 120 or a RAN serving the second
device 122 is able to assist in setting up the unicast SL
connection. The term `RAN` may here denote the cell in which the
relevant device 120 or 122 is located, the operator the relevant
device 120 or 122 is subscribed to, or the radio access technology
(RAT) the relevant device 120 or 122 is using.
[0045] Upon determining the positive in step 302 (i.e. that the RAN
serving the first device 120 or the RAN serving the second device
122 is able to assist in setting up the unicast SL connection), the
method proceeds to step 304A in which the device 120 applies a L1
unicast-based SL connection for setting up the unicast SL
connection. For example, the L1 unicast-based SL connection may be
used as the unicast SL connection between the two devices 120 and
122. It is noted that unicast communication using the L1
unicast-based SL may require an RNTI kind of access stratum (AS)
identifier so that the identifier can be used on a PHY layer (i.e.
on L1) to identify the unicast connection or the receiving UE 120
in the unicast communication.
[0046] Upon determining the negative in step 302 (i.e. that the RAN
serving the first device 120 or the RAN serving the second device
122 is unable to assist in setting up the unicast SL connection),
the method proceeds to step 304B in which the device 120 applies a
L1 broadcast-based SL connection for setting up the unicast SL
connection. For example, the L1 broadcast-based SL connection may
be used as the unicast SL connection between the two devices 120
and 122. Such L1 broadcast connection does not need an RNTI kind of
ID on the AS layer. On the contrary, it is using an upper layer
identifier, such as L2 destination ID, and the required unicast SL
connection may be established via higher layer signaling above AS
layer (e.g. NAS signaling). In other words, there may not be any
need of connection setup using the L1 broadcast-based SL for mere
broadcast communication. However, the required unicast
communication using the L1 broadcast-based SL connection may need
some setup which may be accomplished on a higher layer than L1,
e.g. on medium access layer (MAC). For example, in such L1
broadcast based unicast communication, the L2 destination ID is
partially in PHY/L1 control channel and partially in MAC protocol
data unit (PDU) header. In this way, the receiving UE cannot
identify itself only based on PHY/L1 information but needs to
receive the MAC PDU to check MAC PDU header to know whether the
received PDU is targeted for it or not. Partially for this reason,
L1 unicast-based SL connection may be preferred and used if RAN
coverage is present, as indicated in steps 302 and 304A. However,
in lack of network coverage/assistance, the L1 broadcast-based SL
may be still be used for setting up the unicast communication
partially because the L1 broadcast-based unicast SL does not
require RAN to provide the locally unique ID to be used in L1.
[0047] As shown, according to steps 302-304 the initiator UE/device
120 determines whether L1 unicast-based SL can be provided and
enforced for the needed unicast D2D session. If the serving RAN of
the first device 120 is able to provide assistance for facilitating
L1 unicast-based SL, then the unicast SL connection is set up based
on the L1 unicast-based SL. This may be realised using RAN-level
signaling enhancements as discussed later. Else, if the involved UE
122, which responds to the request from the initiator UE 120 for
the needed unicast D2D session, can benefit from the serving RAN
thereof (i.e. the RAN of the second device 122 is able to provide
needed assistance for facilitating L1 unicast-based SL), then step
304A may be entered as well. Also. this determination may be
realized using RAN-level signaling enhancements, as discussed
later. Else, if neither of the RAN(s) can help, then L1
broadcast-based SL is used.
[0048] Therefore, as explained above, the device 120 may set up the
unicast SL connection and then, in step 306, communicate with the
second device 122 over the unicast SL. This communication may
involve data related to the application requiring unicast SL
connection, as decided in step 300.
[0049] In an embodiment, the deciding of step 300 is based on an
application requiring the unicast SL connection, or the type of the
application. That is, not all applications are determined to
require unicast communication. In one embodiment, an application is
determined as requiring the unicast SL connection if the
application is triggered by the first device 120 for assistance in
at least partly autonomous driving. Autonomous driving is a use
case which may require HRLLC and thus unicast communication may be
beneficial. As some example applications on this field and
requiring unicast communication a see-through application and a
line-switching/merging application (both discussed earlier) may be
mentioned.
[0050] Let us take a closer look on some embodiments with respect
to FIGS. 4, 5 and 6. These figures illustrate signalling procedures
between the initiator UE 120, an involved UE 122 and a serving gNB
(e.g. the gNB 110 or the gNB 112) of the serving RAN over the SL
connection between the two UEs 120, 122 and over the Uu connection
between the UE 120/122 and respective gNB 110/112, according to
some embodiments.
[0051] FIG. 4 shows an embodiment for a case where the serving RAN
of the initiator UE is able to provide the requested assistance for
establishing and using L1 unicast-based SL between the initiator UE
and the involved UE. A precondition for this may be that the
initiator UE 120 is in RRC-connected state of the serving RAN. In
this example embodiment of FIG. 4, both the initiator UE and the
involved UE share the same serving RAN (such as the same cell or
the same operator).
[0052] In step 400, the serving RAN may indicate support for
assisting L1 unicast-based SL, e.g. by using an indication message.
The device 120 may use this for the determination step 302. The
indication serves to tell the receiving UE whether the serving cell
may provide support for L1 unicast-based SL or not, so that the UE
may initially decide to request for the support (i.e., ask for SL
resource allocation in step 404 as explained later). The indication
may not necessarily mean that the serving cell will be able to
assist a particular UE and therefore the UE needs to request for
assistance from the serving cell, e.g. in order to allocate the
radio resources and ID(s).
[0053] In an embodiment, the support indication is cell-specific.
It should be noted that not all cells of the RAN are necessarily
supporting the L1 unicast-based SL even if some cells are. In an
embodiment, the indication is carried over system information block
(SIB). Alternatively, the indication may be UE-specific and
configured to the UE 120 in a dedicated signalling. In an
embodiment, the support indication of step 400 may include a binary
indication where e.g. bit `0` means the RAN/cell does not support
L1 unicast-based SL connection while a bit `1` the RAN/cell
supports L1 unicast-based SL connection, or vice versa.
[0054] In an embodiment, the support indication of step 400 may
include a resource pool. The resource pool may in an embodiment be
intended for all unicast SL communications and not specific to
any-one particular UE. The resource pool may be used by the UE if
using L1 broadcast-based SL or UE autonomous resource
allocation/selection mode. The resource pool may be provided along
with constraints, such as maximum number of unicast SLs per one D2D
communication session. The indication may also comprise an
indication of extended support, such as an indication for
scheduling for intra-cell L1 unicast-based SL when both UEs 120,
122 of the unicast SL connection are served by the cell. The
indication may also specify further criteria/conditions/constraints
such as what kinds of applications or services, UE categories,
radio conditions, and so forth that relevant UE needs to fulfil
before requesting for assistance in step 404.
[0055] The device 120 then proceeds with step 300, i.e. determining
whether the application in question needs the unicast SL connection
or not. Here it is assumed that the application needs such unicast
SL connection.
[0056] In an optional step 402, the first and second devices 120,
122 may exchange basic safety messages (BSM), such as Cooperative
Awareness Message (CAM) and/or Decentralized Environmental
Notification Message (DENM). The UE 120 may determine, based on
reception of BSM, the one or more UEs 122 in proximity that may be
impacted with by the triggering of the application and therefore
need to get involved in the D2D session to be set up for the
application. The need for this step 402 may depend on the
application. For example, in lane-switching scenario all the
impacted vehicles could be identified in advance and be enforced to
get involved, whereas for the see-through application (i.e. an
application requiring see-through) one or more UEs may be capable
and by default willing to get involved to provide the initiator 120
with see-though contents.
[0057] Upon/after determining that the RAN serving the first device
120 is able to assist in setting up the L1 unicast SL connection,
the device 120 may in step 404 send an assistance request message
to the RAN serving the first device 120. The request can be for one
or more L1 unicast-based SL to be set up, as indicated in the
request. It should be noted that even if the serving RAN 110 has
indicated support in step 400, the serving RAN may be unable to
assist at that particular time and/or for that particular UE 120.
Therefore, the assistance request message of step 404 may be
needed.
[0058] The assistance request message may comprise a request for a
radio resource allocation for SL communication of the first device
on the L1 unicast-based SL connection. In an embodiment, the
request may additionally or alternatively be for at least one
locally unique ID (e.g. L1 SL ID), such as a radio network
temporary identifier (RNTI), to be applied for the L1 unicast-based
SL connection on at least the SL radio resources (requested or
received earlier in step 400). In case of RNTI, the RNTI may be
referred to as L1 SL-RNTI. Other IDs than RNTI may be applicable
too and RNTI is used in the following description only as an
example. The at least one locally unique ID may be a locally unique
ID for the at least one SL and/or locally unique IDs for the UE 120
and of the UE 122.
[0059] In step 406, the UE 120 may receive a response from the RAN.
The response may comprise the requested resource allocation for the
L1 unicast-based SL connection from the RAN serving the first
device 120. This resource pool may be dedicated to the requesting
UE's use and/or to the specific SL. However, receiving these
dedicated resources may be optional, e.g. when a resource pool is
indicated in step 400 and the UE autonomous resource allocation is
to be used. The received response may comprise the at least one L1
SL ID (such as the RNTI) to be used on the SL resources. In case
the RAN 110 is not able to assist, the response may comprise an
indication that the requested network assistance for the time being
cannot be provided. However, let us here assume that the assistance
is possible.
[0060] The process may then proceed to step 408 where the UE 120
may determine that the L1 unicast-based SL can be provided and
enforced. Consequently, the UE 120 may in step 410 send an
establishment request of the L1 unicast-based SL connection (i.e. a
D2D unicast connection establishment request) to one or more
targeted UE 122. The establishment request may be sent over L1
broadcast-based SL on local cell-specific SL resources, because the
L1 unicast-based SL connection is not yet set up by the second
device 122. The request may target an individual UE 122 or one more
UEs. In an embodiment, the establishment request may also comprise
an identifier (e.g. a global cell ID) of the RAN serving the first
device 120.
[0061] In one embodiment, the establishment request may include an
indication indicating the initial determination of the initiator UE
120 regarding whether the initiator UE 120 is able to provide and
enforce the L1 unicast-based SL or not (`yes`, in this example of
FIG. 4). In this case (`yes`), the establishment request may
comprise the at least one RNTI for the L1 unicast-based SL
connection and a resource allocation for the SL communication of
the first device 120 on the L1 unicast-based SL connection
corresponding to the at least one RNTI. That is, the L1 SL-RNTI is
valid and locally unique on at least the allocated resources. In
case the UE 120 has received a set of RNTIs to be used for a set of
SL connections, the UE 120 may select one which is to be used in
the SL connection with this particular UE 122 and provide those
(RNTI and corresponding radio resources, e.g. time and frequency
resources) to the UE 122.
[0062] In step 412 the first UE 120 may receive an establishment
response (i.e. D2D unicast connection establishment response) from
the second device 122. This response may be an acknowledgement for
the unicast SL connection based on the L1 unicast-based SL.
[0063] After this response, the UEs 120, 122 (or 120 and one or
more UEs 122 affected by the application run in the device 120) may
in step 414 determine proceed with unicast communication session
utilizing L1 unicast-based SL connection assisted by the serving
RAN of the first device 120.
[0064] The D2D unicast connection establishment response in step
412 may further indicate whether the second UE is out-of-coverage
(0oC) or in-coverage. The response may (in case of in-coverage)
indicate whether the second device 122 is served by the same RAN as
the first device 120 or not (e.g. by indicating an ID (e.g. global
cell ID) of the serving RAN of the second device 122). In case the
second device 122 is served by the same RAN as the first device 120
(as indicated by the determination steps of 416A and 416B), then
the serving RAN may be able to provide more extended assistance.
For example, the RAN may allocate the SL resources using a
corresponding SL-RNTI for the L1 unicast-based SL connection via
PDCCH. In this case scheduling assignment may not be needed for the
SL data transmission.
[0065] In one embodiment related to the case that both UEs 120, 122
are served by the same RAN as depicted in FIG. 4 (and FIG. 1A), the
UE 120 may in step 418B send to the RAN 110 information about the
L1 unicast-based SL connection. The information may identify the
second device 122. From this the RAN may detect that the UE 122 is
also served by the same RAN as the UE 120, and optionally provide
the above mentioned extended assistance. The indication 418B may
also indicate any unused L1 SL-RNTIs out of the allocated set of L1
SL-RNTIs received in step 406. The second device 122 may likewise
send information about the L1 unicast-based SL connection to the
RAN 110 in step 418A.
[0066] Let us then look at FIG. 5. FIG. 5 depicts a case in which
the initiator UE 120 is Out-of-Coverage (0oC) and the involved UE
122 is able to provide and enforce a L1 unicast-based SL to serve
as the unicast connection between the two UEs 120, 122.
[0067] In step 500, the serving RAN 112 (as in FIG. 1B) provides an
indication of support of L1 unicast-based SL connection to the
second UE 122. Here the contents and particulars of this indication
message may be the same as that of the indication message described
in connection of step 400 of FIG. 4.
[0068] Then the first UE 120 may perform the step 300 and also
possibly exchange BSM(s) with the second UE 122. Step 502 may be
the same as the step 402 of FIG. 4.
[0069] Because the UE 120 is out of coverage or at least partly
because the UE 120 has not received any indication of support of L1
unicast-based SL from its own serving RAN (possibly e.g. RAN 110 of
FIG. 1B), the UE 120 may in step 504 perform sensing and/or D2D
resource reservation for the D2D session to be set up. This step
may be preceded by determining the radio resources needed for the
D2D session. The resource reservation may depend on whether the
resources are allocated by the serving RAN or selected by the UE
autonomously. Both may be applied for L1 unicast-based SL and L1
broadcast-based SL, even though network-scheduled resource
allocation is more likely for L1 unicast-based SL and the
autonomous UE resource selection is more likely for L1
broadcast-based SL. The reserving of the radio resources may thus
be done proactively and upon initial determination which of either
L1 unicast SL or L1 broadcast SL is applied, before the unicast D2D
communication is actually set up. E.g. in this case of FIG. 5, the
reserved resource may be on the L1 broadcast-based SL connection.
E.g. when the UE 120 is OoC, then from the UE's perspective SL may
by default rely on L1 broadcast-based SL using preconfigured
resources. That is, the UE may be preconfigured with a resource
pool for 0oC situation and once the UE is 0oC and needs to transmit
on SL, the UE may perform sensing on the preconfigured pool for 0oC
and based on that select resources from the pool for the needed SL
transmission. The UE may rely on preconfigured pool for 0oC
operation, e.g. the resource pool may be part of subscription
profile configuration and/or received earlier when the UE was
in-coverage. This step enables actual unicast D2D communication to
take place as soon as possible and hence speed up the D2D
communication session.
[0070] In step 506, the UE 120 may upon determining that the UE 120
is out of coverage or the RAN serving the first device 120 is
unable to assist, request (e.g. in a D2D unicast connection
establishment request) from the second device 122 establishment of
the unicast SL connection. In one embodiment the request does not
specify which type of unicast connection to set-up (L1
unicast-based or L1 broadcast-based). However, in one embodiment,
the request may specify to set up the L1 broadcast-based SL
connection as the UE 120 is not aware of any possibility to set up
the L1 unicast-based SL. The establishment request may be sent over
L1 broadcast-based SL on resources selected by the UE 120 from the
preconfigured resource pool for 0oC operation. E.g. for the needed
unicast SL communication, the UE 120, even as the receiving end in
some use cases, may select/reserve resources from the preconfigured
pool for the 0oC and indicate those to the intended peer UE 122.
The request may target an individual UE 122 or one more UEs.
[0071] In one embodiment, the establishment request may include an
indication indicating the initial determination of the initiator UE
120 regarding whether the initiator UE 120 is able to provide and
enforce the L1 unicast-based SL or not (`no`, in this example of
FIG. 5). In this case (`no`), the D2D unicast connection
establishment request may comprise an indication that the initiator
UE 120 is out of coverage or that the current serving RAN 110 of
the initiator UE 120 is not able to provide needed network
assistance (e.g. the UE may be in-coverage but the RAN 110 cannot
assist for the time being).
[0072] In an embodiment, the request may comprise an identifier
(e.g. global cell ID) of the radio access network serving the first
device 120, in case the UE 120 is aware of such.
[0073] In an embodiment, the establishment request may also
comprise an indication of the reserved SL resources, but without
any L1 SL-RNTI (as such has not been received by the UE for the SL
communication) for expediting the D2D communication session. The
indicated SL resources may, as said above, be proactively reserved
by the initiator UE 120 either autonomously or allocated by the
serving RAN (e.g. earlier) so that those can be used to
transmit/receive SL to/from the initiator UE 120.
[0074] In an embodiment, the request comprises information needed
by the second device 122 to request resources from the RAN 112
serving the second device 122. The information may in an embodiment
be derivable from the requested application/service. E.g. the
involved UE 112 may determine the needed resources, especially in
case the involved UE 112 is actually the content provider (e.g. in
case of see-though). However, in an embodiment, the information may
comprise at least one of the following: QoS requirements,
preferable QoS constraints or priorities, expected session
lifetime, amount of data to be communicated over SL (e.g. when the
requesting UE needs to transmit), indication of whether the session
may involve other UEs and corresponding SLs.
[0075] The second UE 122, after having received the support
indication in step 500 and having detected that the first UE 120 is
not being assisted by the serving RAN, may in step 508 determine
that L1 unicast-based SL may be an option. Therefore, the UE 122
may in step 510 send an assistance request message to the RAN 112
serving the second device 122. The request can be for one or more
L1 unicast-based SL to be set up. The assistance request message
may further comprise a request for a radio resource allocation for
SL communication of the second device on the L1 unicast-based SL
connection. The request may alternatively or additionally be for at
least one locally unique ID, such as a radio network temporary
identifier (RNTI) to be applied for the L1 unicast-based SL
connection on at least the SL radio resources (requested or
received earlier in step 500). This RNTI may be referred to as L1
SL-RNTI. Other IDs than RNTI may be applicable too and RNTI is used
as one example. The locally unique ID may be a locally unique ID
for the at least one SL and/or locally unique IDs for the UE 120
and of the UE 122.
[0076] In step 512, the UE 122 may receive a response from the RAN
112. The response may include the requested resource allocation for
the L1 unicast-based SL connection from the RAN serving the second
device 122. This resource pool may be dedicated to the requesting
UE's use and/or to the specific SL. However, receiving these
dedicated resources may be optional, e.g. when a resource pool is
indicated in step 400 and the UE autonomous resource allocation is
to be used. The received response may comprise the at least one L1
SL ID (such as the RNTI) to be used on the SL resources. In case
the RAN 112 is not able to assist, the response may comprise an
indication that the requested network assistance for the time being
cannot be provided. However, let us here assume that the assistance
is possible. As a result, the UE 122 may determine in step 514 that
the L1 unicast-based SL is enforced and to be applied.
[0077] Thereafter, the UE 122 may in step 516 send a D2D unicast
connection establishment response to the UE 120. The response may
include an indication that the responding UE 122 is able to provide
and enforce L1 unicast-based SL.
[0078] In one embodiment the RAN 112 may indicate to the requesting
UE 122 a set of L1 SL IDs e.g. in the response of step 512. The UE
122 may indicate these to the initiator UE 120 who can then use
those for setting up plurality of SL connections with a plurality
of involved UEs. In addition to the L1 SL IDs, also dedicated
resource pools for the plurality of SLs may be provided by the RAN
112 to the UE 122 for forwarding to the UE 120, or one resource
pool from which the UE 120 may select appropriate among for each of
the plurality of SLs. This may be beneficial for supporting
critical application such as the lane-merging/switching which may
enforce all the impacts UEs to get involved with the best possible
capability and capacity and prefer to use L1 unicast-based SL
whenever possible.
[0079] The D2D unicast connection establishment response may
further comprise an indication of a cell ID (e.g. global cell ID)
of the serving RAN 112 of the responding UE 122, and/or the
resource allocation received from the RAN 112, and/or the locally
unique ID, such as the L1 SL-RNTI, corresponding to the resource
allocation.
[0080] After this response, the UEs 120, 122 (or 120 and one or
more UEs 122 affected by the application run in the device 120) may
in step 518 determine to proceed with the unicast communication
session utilizing L1 unicast-based SL connection assisted by the
serving RAN 112 of the second device 122, instead of the L1
broadcast-based SL connection.
[0081] A step corresponding to step 418A may exist also in the
example embodiment of FIG. 5. That is, the UE 122 may inform the
serving RAN information regarding the applied L1 unicast-based SL
connection taking place between the UEs 120 and 122. The
information may identify the first device 120 (i.e. the peer UE of
the SL). The indication may also indicate any unused L1 SL-RNTIs
out of the allocated set of L1 SL-RNTIs possibly received in step
512.
[0082] FIG. 6 then depicts a case in which both the initiator UE
120 and the involved UE 122 are Out-of-Coverage. In step 602, the
devices 120, 122 may optionally exchange basic safety messages, as
explained already in connection of step 402. After step 300, the UE
120 may decide that D2D unicast is needed for this application.
[0083] Because the UE 120 has not received any indication of
support of L1 unicast-based SL from its own serving RAN (possibly
because of 0oC situation), the UE 120 may in step 604 perform
sensing and D2D resource reservation for the D2D session to be set
up. This step may be similar to that of step 504.
[0084] After this, the UE 120 (initiator UE) may send establishment
of the unicast SL connection in step 606 to the second UE 122. This
step is the same as that of step 506 of FIG. 5. In step 608, the
second UE 122 after having detected that the second UE cannot
receive assistance from its serving cell (e.g. out-of-coverage
and/or the RAN 110/112 being unable to assist for the time being),
the second UE 122 sends a response to the first UE. The response
may include an indication that the second UE 122 is not able to
provide and enforce the L1 unicast-based SL. E.g. the response may
comprise an indication that the involved UE 122 is out-of-coverage
or that the current serving RAN 110/112 of the UE 122 is not able
to provide needed network assistance (e.g. the UE may be
in-coverage but RAN cannot assist for the time being).
[0085] Based on this, the UE 120 decides to proceed with unicast SL
connection assisted by the L1 broadcast-based SL, instead of being
assisted by L1 unicast-based SL as in FIGS. 4 and 5. The L1
broadcast-based SL used in this example embodiment of FIG. 6 here
means that no RNTI (or similar) ID on the AS layer is being used.
On the contrary, an upper layer identifier, such as L2 destination
ID, is applied and the required unicast SL connection may be
established via higher layer signaling above AS layer (e.g. NAS
signaling), as explained earlier in connection of step 304B.
[0086] In this way, in all the example embodiments presented in
connection of FIGS. 4-6, the UEs may communicate over unicast SL
connection which is beneficial for the low latency and high
reliability requiring applications.
[0087] It may be noted that in the see-through application used as
one example application, the initiator UE 120 is the one which
needs to receive contents (e.g. see-though assisting video streams)
from one or more UEs 122 in front of the initiator UE 120. Thus, in
an embodiment, the setup of unicast SL connection is a
receiver-initiated process.
[0088] In one embodiment where both the initiator UE 120 and the
involved UE 122 share the same serving RAN/cell, C-RNTIs of the UEs
can be utilized for the SL, instead of or in addition to L1 SL ID
(such as the L1 SL-RNTI). For this, D2D unicast connection
establishment request 410 and D2D unicast connection establishment
response 412 may optionally indicate the cellular RNTI (C-RNTI) of
the UEs 120, 122.
[0089] In an embodiment where the initiator UE 120 does not
determine the involved UE(s) 122 beforehand, the initiator UE 120
may use any suitable UE 122 in proximity which responds to the
initiator's request. In this case, there may be a need for a third
D2D message by the UE 120 to the responding UE 122, in addition to
D2D unicast connection establishment request and D2D unicast
connection establishment response, to indicate the SL resource
allocation (including the L1 SL ID), in order to set up the L1
unicast-based SL. These D2D messages may be implemented as D2D
application control messages or control plane SL control messages,
if the control plane is introduced to the SL. Otherwise, MAC CE
based SL control signaling may be used as another option.
[0090] Some of the embodiments presented may help to speed up the
unicast connection setup for the use cases of interest. Some of the
embodiments presented may help to resolve L1 ID issue. For example,
regarding security, a permanent Global UE ID should preferably not
be disclosed in L1 signaling or, that is, current L1 signaling is
not highly protected in term of security and therefore sending a
permanent Global UE ID in L1 signaling is not preferable.
Furthermore, L1 signaling or physical SL control channel (PSCCH)
used to schedule for a radio transmission over SL is rather limited
in the maximum number of bits and therefore using a long global UE
ID on PSCCH is not preferable. The solution may allow unicast D2D
using L1 unicast-based SL whenever possible and otherwise using L1
broadcast-based SL where unicast connection is realized on higher
layer using existing higher-layer UE IDs.
[0091] Although the description is written partly so that the UE
120 is to set up one SL with the UE 122, the UE 120 may decide to
set up multiple SLs with multiple second UEs 122, depending on the
need of the application in question.
[0092] Although the description in some instances refers to the UE
120 and the one or more UEs 122 being vehicular devices, the UEs
120, 122 need not necessarily be vehicular devices and the proposal
is valid for any devices/UEs. However, in one embodiment, the
device 120, 122 are vehicular devices, such as autos or
motorcycles.
[0093] From the point of view of the second device 122, the
proposal may comprise e.g. receiving a request for unicast
connection establishment (i.e. the D2D unicast connection
establishment request explained above) from the first device 120.
In one embodiment, the establishment request may be sent over L1
broadcast-based SL. In an embodiment, the establishment request may
also comprise an identifier (e.g. a global cell ID) of the RAN
serving the first device 120. In one embodiment, the establishment
request may include an indication indicating whether the initiator
UE 120 is able to provide and enforce the L1 unicast-based SL or
not.
[0094] In case of (`yes`), the establishment request may comprise
at least one RNTI for the L1 unicast-based SL connection and a
resource allocation for the SL communication of the first device
120 on the L1 unicast-based SL connection corresponding to the at
least one RNTI. That is, the L1 SL-RNTI is valid and locally unique
on at least the allocated resources. Then the UE 122 may respond to
the request by sending the D2D unicast connection establishment
response. The response may in an embodiment indicate whether the
second UE is out-of-coverage (OoC) or in-coverage. The response may
further (in case of in-coverage) indicate whether the second device
122 is served by the same RAN as the first device 120 or not (e.g.
by indicating an ID (e.g. global cell ID) of the serving RAN of the
second device 122). In this case, the second UE 122 may proceed
with unicast SL connection by applying the L1 unicast-based SL
assisted by the RAN of the first UE 120.
[0095] In case of (`no), and after having determined that the RAN
of the second UE is able to assist setting up the unicast SL
connection based on L1 unicast-based SL, the second UE may send an
assistance request message to the RAN 112 serving the second device
122, as explained in step 510. The request can be for one or more
L1 unicast-based SL to be set up. The assistance request message
may further comprise a request for a radio resource allocation for
SL communication of the second device on the L1 unicast-based SL
connection. The request may alternatively or additionally be for at
least one locally unique ID, such as a radio network temporary
identifier (RNTI) to be applied for the L1 unicast-based SL
connection on at least the SL radio resources (requested or
received earlier in step 500). This RNTI may be referred to as L1
SL-RNTI. Other IDs than RNTI may be applicable too and RNTI is used
as one example. Said more generally, the locally unique ID may be a
locally unique ID for the at least one SL and/or locally unique IDs
for the UE 120 and of the UE 122. Then, the UE 122 may receive a
response from the RAN 112. The response may include the requested
resource allocation for the L1 unicast-based SL connection from the
RAN serving the second device 122. This resource pool may be
dedicated to the requesting UE's use and/or to the specific SL.
However, receiving these dedicated resources may be optional, e.g.
when a resource pool is indicated in step 500 and the UE autonomous
resource allocation is to be used. The received response may
comprise the at least one L1 SL ID (such as the RNTI) to be used on
the SL resources. From the RAN response, the UE 122 may determine
in step 514 that the L1 unicast-based SL is enforced and to be
applied. Thereafter, the UE 122 may send a D2D unicast connection
establishment response to the UE 120. The D2D unicast connection
establishment may include an indication that the responding UE 122
is able to provide and enforce L1 unicast-based SL. The D2D unicast
connection establishment may further comprise an indication of at
least one of the following: a cell ID (e.g. global cell ID) of the
serving RAN 112 of the responding UE 122, a L1 SL-RNTI received and
radio resources on which L1 SL-RNTI is locally unique. In this
case, the second UE 122 may proceed with unicast SL connection by
applying the L1 unicast-based SL assisted by the RAN of the second
UE 122.
[0096] In case of `no` and having detected that the RAN serving the
second UE 122 is also unable to assist in setting up the L1
unicast-based SL connection, the second UE 122 may respond to first
UE with an indication that the second UE 122 is not able to provide
and enforce the L1 unicast-based SL. In this case, the second 122
may proceed with unicast SL connection by applying the L1
broadcast-based SL.
[0097] From the point of view of the radio access network (or a
control node 110/112 of the serving RAN), the proposal may comprise
e.g. providing an indication to a device 120, 122, wherein the
indication indicates that the RAN supports the device to set up a
unicast SL connection based on a L1 unicast-based SL connection.
The proposal may further comprise the control node of the RAN
receiving, from the device, a request for assistance in setting up
the unicast SL connection with another device. In one embodiment,
the request may comprise a request for a radio resource allocation
for the SL communication of the device on the L1 unicast-based SL
connection. In one embodiment, the request may further be for at
least one radio network temporary identifier (RNTI) to be applied
as a locally unique ID for the L1 unicast-based SL connection on at
least the requested radio resources. This RNTI may be referred to
as L1 SL-RNTI. Other IDs than RNTI may be applicable too and RNTI
is used as one example. The locally unique ID may be a locally
unique ID for the at least one SL and/or locally unique IDs for the
devices participating in the SL. Then, in response to receiving the
request, the control node of the RAN may provide to the requesting
device at least a resource allocation for the L1 unicast-based SL
connection. In one embodiment, the provided resource allocation may
further include the at least one RNTI to be used on the allocated
resources. In one embodiment, in case the RAN serves both of the
UEs involved in the SL communication, the control node of the RAN
may allocate the resources by using the corresponding L1 SL-RNTI
for the L1 unicast-based SL connection via a PDCCH.
[0098] An embodiment, as shown in FIG. 7, provides an apparatus 10
comprising a control circuitry (CTRL) 12, such as at least one
processor, and at least one memory 14 including a computer program
code (PROG), wherein the at least one memory and the computer
program code (PROG), are configured, with the at least one
processor, to cause the apparatus to carry out any one of the
above-described processes. The memory may be implemented using any
suitable data storage technology, such as semiconductor-based
memory devices, flash memory, magnetic memory devices and systems,
optical memory devices and systems, fixed memory and removable
memory.
[0099] In an embodiment, the apparatus 10 may comprise the terminal
device of a communication system, e.g. a user terminal (UT), a
computer (PC), a laptop, a tabloid computer, a cellular phone, a
mobile phone, a communicator, a smart phone, a palm computer, a
mobile transportation apparatus (such as a car), a household
appliance, a device, or any other communication apparatus, commonly
called as UE or device in the description. Alternatively, the
apparatus is comprised in such a terminal device. Further, the
apparatus may be or comprise a module (to be attached to the UE)
providing connectivity, such as a plug-in unit, an "USB dongle", or
any other kind of unit. The unit may be installed either inside the
UE or attached to the UE with a connector or even wirelessly. In an
embodiment, the apparatus may be comprised or comprise the first
device 120. In an embodiment, the apparatus may be comprised or
comprise the second device 122.
[0100] The apparatus may further comprise communication interface
(TRX) 16 comprising hardware and/or software for realizing
communication connectivity according to one or more communication
protocols. The TRX may provide the apparatus with communication
capabilities to access the radio access network, for example. The
apparatus may also comprise a user interface 18 comprising, for
example, at least one keypad, a microphone, a touch display, a
display, a speaker, etc. The user interface may be used to control
the apparatus by the user.
[0101] The control circuitry 12 may comprise a D2D access control
circuitry 20 for controlling access and use of resources on a D2D
link, for determining whether to apply L1 unicast-based SL or L1
broadcast-based SL for the unicast connection. according to any of
the embodiments. The control circuitry 12 may comprise a network
access control circuitry 22 e.g. accessing and communicating with a
network, such as cellular radio access network, according to any of
the embodiments.
[0102] An embodiment, as shown in FIG. 8, provides an apparatus 50
comprising a control circuitry (CTRL) 52, such as at least one
processor, and at least one memory 54 including a computer program
code (PROG), wherein the at least one memory and the computer
program code (PROG), are configured, with the at least one
processor, to cause the apparatus to carry out any one of the
above-described processes. The memory may be implemented using any
suitable data storage technology, such as semiconductor-based
memory devices, flash memory, magnetic memory devices and systems,
optical memory devices and systems, fixed memory and removable
memory.
[0103] In an embodiment, the apparatus 10 may be or be comprised in
a network node of the radio access network, such as in
gNB/gNB-CU/gNB-DU of 5G or in eNB/eNB-CU/eNB-DU of EUTRA. In an
embodiment, the apparatus 10 is or is comprised in the network node
110 or 112.
[0104] It should be appreciated that future networks may utilize
network functions virtualization (NFV) which is a network
architecture concept that proposes virtualizing network node
functions into "building blocks" or entities that may be
operationally connected or linked together to provide services. A
virtualized network function (VNF) may comprise one or more virtual
machines running computer program codes using standard or general
type servers instead of customized hardware. Cloud computing or
data storage may also be utilized. In radio communications, this
may mean node operations to be carried out, at least partly, in a
central/centralized unit, CU, (e.g. server, host or node)
operationally coupled to distributed unit, DU, (e.g. a radio
head/node). It is also possible that node operations will be
distributed among a plurality of servers, nodes or hosts. It should
also be understood that the distribution of labour between core
network operations and base station operations may vary depending
on implementation.
[0105] In an embodiment, the server may generate a virtual network
through which the server communicates with the radio node. In
general, virtual networking may involve a process of combining
hardware and software network resources and network functionality
into a single, software-based administrative entity, a virtual
network. Such virtual network may provide flexible distribution of
operations between the server and the radio head/node. In practice,
any digital signal processing task may be performed in either the
CU or the DU and the boundary where the responsibility is shifted
between the CU and the DU may be selected according to
implementation.
[0106] Therefore, in an embodiment, a CU-DU architecture is
implemented. In such case the apparatus 50 may be comprised in a
central unit (e.g. a control unit, an edge cloud server, a server)
operatively coupled (e.g. via a wireless or wired network) to a
distributed unit (e.g. a remote radio head/node). That is, the
central unit (e.g. an edge cloud server) and the radio node may be
stand-alone apparatuses communicating with each other via a radio
path or via a wired connection. Alternatively, they may be in a
same entity communicating via a wired connection, etc. The edge
cloud or edge cloud server may serve a plurality of radio nodes or
a radio access networks. In an embodiment, at least some of the
described processes may be performed by the central unit. In
another embodiment, the apparatus 50 may be instead comprised in
the distributed unit, and at least some of the described processes
may be performed by the distributed unit.
[0107] In an embodiment, the execution of at least some of the
functionalities of the apparatus 50 may be shared between two
physically separate devices (DU and CU) forming one operational
entity. Therefore, the apparatus may be seen to depict the
operational entity comprising one or more physically separate
devices for executing at least some of the described processes. In
an embodiment, such CU-DU architecture may provide flexible
distribution of operations between the CU and the DU. In practice,
any digital signal processing task may be performed in either the
CU or the DU and the boundary where the responsibility is shifted
between the CU and the DU may be selected according to
implementation. In an embodiment, the apparatus 10 controls the
execution of the processes, regardless of the location of the
apparatus and regardless of where the processes/functions are
carried out.
[0108] The apparatus may further comprise communication interface
(TRX) 56 comprising hardware and/or software for realizing
communication connectivity according to one or more communication
protocols. The TRX may provide the apparatus with communication
capabilities to access the radio access network, for example. The
apparatus may also comprise a user interface 58 comprising, for
example, at least one keypad, a microphone, a touch display, a
display, a speaker, etc. The user interface may be used to control
the apparatus by the user.
[0109] The control circuitry 52 may comprise an D2D control
circuitry 60 for controlling D2D related aspects, such as resource
allocation, ID allocation, or setting-up of the L1 unicast-based
SL, according to any of the embodiments. The control circuitry 52
may comprise a network access control circuitry 62 for controlling
mobile access to the network via the apparatus 50.
[0110] In an embodiment, an apparatus carrying out at least some of
the embodiments described comprises at least one processor and at
least one memory including a computer program code, wherein the at
least one memory and the computer program code are configured, with
the at least one processor, to cause the apparatus to carry out the
functionalities according to any one of the embodiments described.
According to an aspect, when the at least one processor executes
the computer program code, the computer program code causes the
apparatus to carry out the functionalities according to any one of
the embodiments described. According to another embodiment, the
apparatus carrying out at least some of the embodiments comprises
the at least one processor and at least one memory including a
computer program code, wherein the at least one processor and the
computer program code perform at least some of the functionalities
according to any one of the embodiments described. Accordingly, the
at least one processor, the memory, and the computer program code
form processing means for carrying out at least some of the
embodiments described. According to yet another embodiment, the
apparatus carrying out at least some of the embodiments comprises a
circuitry including at least one processor and at least one memory
including computer program code. When activated, the circuitry
causes the apparatus to perform the at least some of the
functionalities according to any one of the embodiments
described.
[0111] As used in this application, the term `circuitry` refers to
all of the following: (a) hardware-only circuit implementations,
such as implementations in only analog and/or digital circuitry,
and (b) combinations of circuits and soft-ware (and/or firmware),
such as (as applicable): (i) a combination of processor(s) or (ii)
portions of processor(s)/software including digital signal
processor(s), software, and memory(ies) that work together to cause
an apparatus to perform various functions, and (c) circuits, such
as a microprocessor(s) or a portion of a microprocessor(s), that
require software or firmware for operation, even if the software or
firmware is not physically present. This definition of `circuitry`
applies to all uses of this term in this application. As a further
example, as used in this application, the term `circuitry` would
also cover an implementation of merely a processor (or multiple
processors) or a portion of a processor and its (or their)
accompanying software and/or firmware. The term `circuitry` would
also cover, for example and if applicable to the particular
element, a baseband integrated circuit or applications processor
integrated circuit for a mobile phone or a similar integrated
circuit in a server, a cellular network device, or another network
device.
[0112] In an embodiment, at least some of the processes described
may be carried out by an apparatus comprising corresponding means
for carrying out at least some of the described processes. Some
example means for carrying out the processes may include at least
one of the following: detector, processor (including dual-core and
multiple-core processors), digital signal processor, controller,
receiver, transmitter, encoder, decoder, memory, RAM, ROM,
software, firmware, display, user interface, display circuitry,
user interface circuitry, user interface software, display
software, circuit, antenna, antenna circuitry, and circuitry.
[0113] The techniques and methods described herein may be
implemented by various means. For example, these techniques may be
implemented in hardware (one or more devices), firmware (one or
more devices), software (one or more modules), or combinations
thereof. For a hardware implementation, the apparatus(es) of
embodiments may be implemented within one or more
application-specific integrated circuits (ASICs), digital signal
processors (DSPs), digital signal processing devices (DSPDs),
programmable logic devices (PLDs), field programmable gate arrays
(FPGAs), processors, controllers, micro-controllers,
microprocessors, other electronic units designed to perform the
functions described herein, or a combination thereof. For firmware
or software, the implementation can be carried out through modules
of at least one chip set (e.g. procedures, functions, and so on)
that perform the functions described herein. The software codes may
be stored in a memory unit and executed by processors. The memory
unit may be implemented within the processor or externally to the
processor. In the latter case, it can be communicatively coupled to
the processor via various means, as is known in the art.
Additionally, the components of the systems described herein may be
rearranged and/or complemented by additional components in order to
facilitate the achievements of the various aspects, etc., described
with regard thereto, and they are not limited to the precise
configurations set forth in the given figures, as will be
appreciated by one skilled in the art.
[0114] Embodiments as described may also be carried out in the form
of a computer process defined by a computer program or portions
thereof. Embodiments of the methods described may be carried out by
executing at least one portion of a computer program comprising
corresponding instructions. The computer program may be in source
code form, object code form, or in some intermediate form, and it
may be stored in some sort of carrier, which may be any entity or
device capable of carrying the program. For example, the computer
program may be stored on a computer program distribution medium
readable by a computer or a processor. The computer program medium
may be, for example but not limited to, a record medium, computer
memory, read-only memory, electrical carrier signal,
telecommunications signal, and software distribution package, for
example. The computer program medium may be a non-transitory
medium. Coding of software for carrying out the embodiments as
shown and described is well within the scope of a person of
ordinary skill in the art.
[0115] Following is a list of some aspects of the invention.
[0116] According to a first aspect, there is provided a method at a
first user equipment, the method comprising: deciding to set up a
unicast sidelink, SL, connection with a second user equipment;
determining whether or not a radio access network serving the first
user equipment or a radio access network serving the second user
equipment is able to assist in setting up the unicast SL
connection; performing one of the following: upon determining the
positive, applying a L1 unicast-based SL connection for setting up
the unicast SL connection, upon determining the negative, applying
a L1 broadcast-based SL connection for setting up the unicast SL
connection; and communicating with the second user equipment over
the unicast SL.
[0117] Various embodiments of the first aspect may comprise at
least one feature from the following bulleted list: [0118]
determining an application requesting the connection; and
performing the deciding based on the application. [0119] wherein
the application requires the unicast SL connection if the
application is triggered by the first user equipment for assistance
in at least partly autonomous driving. [0120] wherein the
application requires the unicast SL connection if the application
is at least one of a group comprising: a see-through application
and a line-switching application. [0121] wherein the application
requires the unicast SL connection if the application is at least
one of a group comprising: a see-through application and a
line-switching application. [0122] wherein the determining
comprises receiving, from the radio access network serving the
first vehicular user equipment, an indication of a support for
setting up the L1 unicast-based SL connection. [0123] determining
that the radio access network serving the first user equipment is
able to assist in setting up the L1 unicast SL connection;
requesting from the radio access network serving the first user
equipment at least one locally unique identifier to be applied for
the L1 unicast-based SL connection; and receiving the at least one
locally unique identifier from the radio access network serving the
first user equipment. [0124] determining that the radio access
network serving the first user equipment is able to assist in
setting up the L1 unicast SL connection; requesting from the radio
access network serving the first user equipment at least one
locally unique identifier to be applied for the L1 unicast-based SL
connection; and receiving the at least one locally unique
identifier from the radio access network serving the first user
equipment. [0125] requesting from the radio access network serving
the first user equipment a resource allocation for the L1
unicast-based SL connection; and receiving the resource allocation
for the L1 unicast-based SL connection from the radio access
network serving the first user equipment. [0126] determining that
the radio access network serving the first user equipment is able
to assist in setting up the L1 unicast SL connection; sending to
the second user equipment, an establishment request for the L1
unicast-based SL connection; and communicating with the second user
equipment over the L1 unicast-based SL connection. [0127] wherein
the establishment request comprises at least one locally unique
identifier for the L1 unicast-based SL connection and a resource
allocation for the L1 unicast-based SL connection corresponding to
the at least one locally unique ID. [0128] receiving an
establishment response from the second user equipment; determining
from the establishment response that the second user equipment is
served by the same radio access network as the first user
equipment; and sending, to the radio access network serving the
first user equipment, an indication of the identity of the second
user equipment. [0129] determining that the radio access network
serving the first user equipment is unable to assist; and sending
to the second user equipment, an establishment request for the
unicast SL connection. [0130] proactively reserving resources for
the unicast SL connection before the SL connection is set up; and
including an indication of the resources in the establishment
request. [0131] receiving an establishment response from the second
user equipment indicating that the radio access network of the
second user equipment is able to assist in setting up the L1
unicast-based SL connection, wherein the establishment response
includes at least one locally unique identifier to be applied for
the L1 unicast-based SL connection; and communicating with the
second user equipment over the L1 unicast-based SL connection,
instead of the L1 broadcast-based SL connection.
[0132] According to a second aspect, there is provided an
apparatus, comprising: at least one processor and at least one
memory including a computer program code, wherein the at least one
memory and the computer program code are configured, with the at
least one processor, to cause a first user equipment to perform
operations comprising: deciding to set up a unicast sidelink, SL,
connection with a second user equipment; determining whether or not
a radio access network serving the first user equipment or a radio
access network serving the second user equipment is able to assist
in setting up the unicast SL connection; performing one of the
following: upon determining the positive, applying a L1
unicast-based SL connection for setting up the unicast SL
connection, upon determining the negative, applying a L1
broadcast-based SL connection for setting up the unicast SL
connection; and communicating with the second user equipment over
the unicast SL.
[0133] Various embodiments of the second aspect may comprise at
least one feature from the bulleted list under the first
aspect.
[0134] According to a third aspect, there is provided a computer
program product embodied on a distribution medium readable by a
computer and comprising program instructions which, when loaded
into an apparatus, execute the method according to the first
aspect. Various embodiments of the third aspect may comprise at
least one feature from the bulleted list under the first
aspect.
[0135] According to a fourth aspect, there is provided a computer
program product comprising program instructions which, when loaded
into an apparatus, execute the method according to the first
aspect. Various embodiments of the fourth aspect may comprise at
least one feature from the bulleted list under the first
aspect.
[0136] According to a fifth aspect, there is provided an apparatus,
comprising means for performing the method according to according
to the first aspect, and/or means configured to cause the first
user equipment to perform the method according to the first aspect.
Various embodiments of the fifth aspect may comprise at least one
feature from
[0137] the bulleted list under the first aspect. According to a
sixth aspect, there is provided an apparatus, comprising at least
one processor and at least one memory including a computer program
code, wherein the at least one memory and the computer program code
are configured, with the at least one processor, to cause a second
user equipment to perform operations comprising: receiving an
establishment request for a unicast sidelink, SL, connection
establishment from the first user equipment, the request indicating
whether the first user equipment is able to enforce a L1
unicast-based SL connection or not; upon detecting that the first
user equipment is able to enforce the L1 unicast-based SL
connection, performing the following: extracting from the
establishment request at least one locally unique identifier for
the L1 unicast-based SL connection and a resource allocation for
the SL communication corresponding to the at least one locally
unique identifier, and communicating with the first user equipment
over the L1 unicast-based SL connection; upon detecting that the
first user equipment is not able to enforce the L1 unicast-based SL
connection, performing the following: determining whether a radio
access network serving the second user equipment is able to assist
in setting up the L1 unicast SL connection or not; upon determining
the positive, performing the following: requesting and receiving
from the radio access network serving the second user equipment at
least one at least one locally unique identifier for the L1
unicast-based SL connection, responding to the first user
equipment, wherein the response includes the at least one locally
unique identifier and a resource allocation for the SL
communication corresponding to the at least one locally unique
identifier, and communicating with the first user equipment over
the L1 unicast-based SL connection; upon determining the negative,
performing the following: communicating with the first user
equipment over a L1 broadcast-based SL connection.
[0138] According to a seventh aspect, there is provided an
apparatus, comprising at least one processor and at least one
memory including a computer program code, wherein the at least one
memory and the computer program code are configured, with the at
least one processor, to cause a control node of a radio access
network to perform operations comprising: providing an indication
to a user equipment, wherein the indication indicates that the
radio access network supports the UE to set up a unicast sidelink,
SL, connection based on a L1 unicast-based SL connection;
receiving, from the user equipment, a request for assistance in
setting up the unicast SL connection with another user equipment,
the request comprising at least a request for at least one locally
unique identifier to be applied for the L1 unicast-based SL
connection; and in response to receiving the request, providing to
the requesting user equipment at least the at least one locally
unique identifier to be applied for the L1 unicast-based SL
connection.
[0139] Even though the invention has been described above with
reference to an example according to the accompanying drawings, it
is clear that the invention is not restricted thereto but can be
modified in several ways within the scope of the appended claims.
Therefore, all words and expressions should be interpreted broadly
and they are intended to illustrate, not to restrict, the
embodiment. It will be obvious to a person skilled in the art that,
as technology advances, the inventive concept can be implemented in
various ways. Further, it is clear to a person skilled in the art
that the described embodiments may, but are not required to, be
combined with other embodiments in various ways.
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